Highlights
- •We compared two different 3D dose reconstruction techniques.
- •Mobius and PerFRACTION were used.
- •PerFRACTION had wider range of dose difference for in vivo dosimetry.
Abstract
We clarified the reconstructed 3D dose difference between two different commercial
software programs (Mobius3D v2.0 and PerFRACTION v1.6.4).
Five prostate cancer patients treated with IMRT (74 Gy/37 Fr) were studied. Log files
and cine EPID images were acquired for each fraction. 3D patient dose was reconstructed
using log files (Mobius3D) or log files with EPID imaging (PerFRACTION). The treatment
planning dose was re-calculated on homogeneous and heterogeneous phantoms, and log
files and cine EPID images were acquired. Measured doses were compared with the reconstructed
point doses in the phantom. Next, we compared dosimetric metrics (mean dose for PTV,
rectum, and bladder) calculated by Mobius3D and PerFRACTION for all fractions from
five patients.
Dose difference at isocenter between measurement and reconstructed dose for two software
programs was within 3.0% in both homogeneous and heterogeneous phantoms. Moreover,
the dose difference was larger using skip arc plan than that using full arc plan,
especially for PerFRACTION (e.g., dose difference at isocenter for PerFRACTION: 0.34%
for full arc plan vs. −4.50% for skip arc plan in patient 1).
For patients, differences in dosimetric parameters were within 1% for almost all fractions.
PerFRACTION had wider range of dose difference between first fraction and the other
fractions than Mobius3D (e.g., maximum difference: 0.50% for Mobius3D vs. 1.85% for
PerFRACTION), possibly because EPID may detect some types of MLC positioning errors
such as miscalibration errors or mechanical backlash which cannot be detected by log
files, or that EPID data might include image acquisition failure and image noise.
Keywords
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Article info
Publication history
Accepted:
December 23,
2017
Received in revised form:
December 18,
2017
Received:
May 4,
2017
Identification
Copyright
© 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
